Problems with Greenhouse Gas Life Cycle Analyses of U.S. LNG Exports and Locally Produced Coal

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The decay rate of methane in the atmosphere will also depend upon the absolute concentration - about 600 ppb (C-600). The rate of biological removal increases linearly up to 0.1% methane in the air. You will see this as a decreasing lifetime in the atmosphere which is an instability not included in the thinking on this subject. Some of the emission data on oil fields is very suspect. For example an aerial survey of So. California will include all the natural methane seeps. These natural seeps provided a lot of business for SCS engineers decades ago and had nothing to do with the oil/gas industry. People who live in So. Calif. have all visited the La Brea Tar pits as children. You get to see all the ice age animals' bones trapped in these natural oil seeps. You see bubbles of methane in the oil even today. One of the major hold-ups in building our underground transit line in LA was the incompetent design relative to natural methane seeps that they discovered could make explosive concentrations with their design. They had a high permeability area between the inner wall and the dirt. Any leak in the inner water could be fed by any seep along the whole path. These leak numbers like 3% or 5% leaks are insane. Just look at the billions of dollars worth of gas involved with any significant leak and the explosion hazards associated with even 0.001% leak on a major line. All the household lines that are small enough to have leaks without blowing up the house (not as common as half a century ago) have pipelines pressure-tested as per building codes. You must pressurize the line with a pressure gauge and it can't lose pressure. Remember leaks are point sources but seeps are all over the place. Putting a plastic barrier under a house on a sand layer above the soil with venting to a permanently light torch was common in Newport Beach.